Re: [igt-dev] [PATCH i-g-t v6 1/3] lib/igt_device: add igt_device_get_pci_addr by fd

["Zbigniew Kempczyński" <zbigniew.kempczynski@intel.com>]

On Wed, Jul 24, 2019 at 02:32:54PM +0200, Daniel Mrzyglod wrote:
> From: Michał Winiarski <michal.winiarski@intel.com>
> 
> This function get us pci address based by fd.
> It allows us to make things a little bit more generic.
> Also, we now require fd rather than doing guesswork when it comes to pci address.
> 
> v4: close sysfs fd
> Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> CC: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
> Signed-off-by: Daniel Mrzyglod <daniel.t.mrzyglod@intel.com>

<cut>

> +struct igt_pci_addr {
> +	unsigned int domain;
> +	unsigned int bus;
> +	unsigned int device;
> +	unsigned int function;
> +};
> +
> +static int igt_device_get_pci_addr(int fd, struct igt_pci_addr *pci)
> +{
> +	char path[IGT_DEV_PATH_LEN];
> +	char *buf;
> +	int sysfs;
> +	int len;
> +
> +	if (!igt_device_is_pci(fd))
> +		return -ENODEV;
> +
> +	sysfs = igt_sysfs_open(fd);
> +	if (sysfs == -1)
> +		return -ENOENT;
> +
> +	len = readlinkat(sysfs, "device", path, sizeof(path) - 1);
> +	close(sysfs);
> +	if (len == -1)
> +		return -ENOENT;
> +	path[len] = '\0';
> +
> +	buf = strrchr(path, '/');
> +	if (!buf)
> +		return -ENOENT;
> +
> +	if (sscanf(buf, "/%4x:%2x:%2x.%2x",
> +		   &pci->domain, &pci->bus,
> +		   &pci->device, &pci->function) != 4) {
> +		igt_warn("Unable to extract PCI device address from '%s'\n", buf);
> +		return -ENOENT;
> +	}
> +
> +	return 0;
> +}

According to kernel: drivers/pci/probe.c, pci_setup_device() device
is formatted using "%04x:%02x:%02x.%d".
Anyway your code will work properly for our case because there's no %02x
on the pci function position.

Acked-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>

> +
> +static struct pci_device *__igt_device_get_pci_device(int fd)
> +{
> +	struct igt_pci_addr pci_addr;
> +	struct pci_device *pci_dev;
> +
> +	if (igt_device_get_pci_addr(fd, &pci_addr)) {
> +		igt_warn("Unable to find device PCI address\n");
> +		return NULL;
> +	}
> +
> +	if (pci_system_init()) {
> +		igt_warn("Couldn't initialize PCI system\n");
> +		return NULL;
> +	}
> +
> +	pci_dev = pci_device_find_by_slot(pci_addr.domain,
> +					  pci_addr.bus,
> +					  pci_addr.device,
> +					  pci_addr.function);
> +	if (!pci_dev) {
> +		igt_warn("Couldn't find PCI device %04x:%02x:%02x:%02x\n",
> +			 pci_addr.domain, pci_addr.bus,
> +			 pci_addr.device, pci_addr.function);
> +		return NULL;
> +	}
> +
> +	if (pci_device_probe(pci_dev)) {
> +		igt_warn("Couldn't probe PCI device\n");
> +		return NULL;
> +	}
> +
> +	return pci_dev;
> +}
> +
> +/**
> + * igt_device_get_pci_device:
> + *
> + * @fd: the device
> + *
> + * Looks up the main graphics pci device using libpciaccess.
> + *
> + * Returns:
> + * The pci_device, skips the test on any failures.
> + */
> +struct pci_device *igt_device_get_pci_device(int fd)
> +{
> +	struct pci_device *pci_dev;
> +
> +	pci_dev = __igt_device_get_pci_device(fd);
> +	igt_require(pci_dev);
> +
> +	return pci_dev;
> +}
> diff --git a/lib/igt_device.h b/lib/igt_device.h
> index 9d7dc2c3..278ba7a9 100644
> --- a/lib/igt_device.h
> +++ b/lib/igt_device.h
> @@ -32,5 +32,6 @@ int __igt_device_drop_master(int fd);
>  void igt_device_drop_master(int fd);
>  
>  int igt_device_get_card_index(int fd);
> +struct pci_device *igt_device_get_pci_device(int fd);
>  
>  #endif /* __IGT_DEVICE_H__ */
> -- 
> 2.20.1
> 
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